A wireless local area network (WLAN) system may employ dynamic frequency selection (DFS) to select the best channel on which to operate, typically to avoid an interference event or interferers which may be other WLAN systems or unrelated devices emitting RF energy, or to avoid interfering with other devices such as radars. Such a system may be primarily intended to avoid interfering with other devices, particularly radars, in order to meet regulatory requirements. However, such systems do not perform well in response to a catastrophic interferer. A catastrophic interferer may be defined as one that causes a significant or total reduction in available throughput. A catastrophic interferer may be a non-WLAN device, or a WLAN device using an extremely aggressive channel access mechanism. Such channel access mechanisms may be employed by a centrally controlled WLAN system in which an access point (AP) may assume that it has complete control of the channel and which may not defer its transmissions to other transmitters if it finds the channel busy.
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